One or more embodiments of the invention generally relate to the use of vibration signatures to monitor an instrumented structure or tank. More particularly, certain embodiments of the invention relates to structural health monitoring and/or non-invasive tank fluid level measurement including cryogenic and zero g environments.
The following background information may present examples of specific aspects of the prior art (e.g., without limitation, approaches, facts, or common wisdom) that, while expected to be helpful to further educate the reader as to additional aspects of the prior art, is not to be construed as limiting the present invention, or any embodiments thereof, to anything stated or implied therein or inferred thereupon.
It is believed that verification of structural integrity by current methods may be either too expensive, too time consuming (requiring highly trained analysts (ultrasonic, thermographs, x-ray, piezo sensor impedance) and/or may show all types of faults including non-critical areas which may require interruption and become highly complex to allow a system which provides a near real time in-Sutu software based indicator when the structure has dangerous defects and may fail. It is believed that current methods of health monitoring and non-destructive evaluation may actively rely on electromagnetic waves or sound waves from an active source in the structure and analyze the reflections or interference caused by defects or passive methods that use the energy released as defects occur to listen to the released energy.
It is believed that current methods to determine the amount of fluid in a tank may require penetrations for the sensors which may allow leakage and in cryogenic fluids to contribute to heat loss. It is believed that in micro-gravity (very low g) environments such as space flight the fluid often moves about (floats) in the container and may prevent existing methods from accurate measurement.
The following is an example of a specific aspect in the prior art that, while expected to be helpful to further educate the reader as to additional aspects of the prior art, is not to be construed as limiting the present invention, or any embodiments thereof, to anything stated or implied therein or inferred thereupon. This invention uses a piezoelectric transducer to vibrate a membrane which is affected in its response by damping of a liquid.
By way of educational background, another aspect of the prior art generally useful to be aware of is that a method includes providing time series structural response data from a structure.
By way of educational background, another aspect of the prior art generally useful to be aware of is that an active damage interrogation (ADI) system (and method) utilizes an array of Piezoelectric transducers attached to or embedded within the structure for both actuation and sensing.
By way of educational background, another aspect of the prior art generally useful to be aware of is that a system and method for structural health monitoring (SHM) of a physical structure, such as an aircraft component, is described. The system may comprise a central data acquisition module and a plurality of wireless, self-contained sensor wafers bonded to a surface of the physical structure.
In view of the foregoing, it is clear that these traditional techniques are not perfect and leave room for more optimal approaches.
Unless otherwise indicated illustrations in the figures are not necessarily drawn to scale.